In the context of this description, the term “fluid” refers to any desired liquid and/or gaseous flow medium or pressure medium. The plug-type connection of this invention is therefore suitable for both hydraulic, pneumatic and also hydropneumatic applications. However, a preferred field of application of the plug-type connection according to the invention is the connection of fuel lines in motor vehicles.
A plug-type connection of the generic type of this invention is described in DE-A 2 414 828 or corresponding U.S. Pat. No. 3,930,674. In this case, a plug-in and locking principle is provided, according to which both coupling parts each have one of two outer annular flanges which are axially adjacent in the plugged-in state and are locked with a clip-like retaining element. To this end, the retaining element is designed as a partial-ring-shaped, flexible clip which is approximately C-shaped in plan view and has two diametrically opposite end sections which are C-shaped in axial section and axially and radially enclose the flanges of the coupling parts. Such a plug-type connection, at relatively low assembly forces, ensures high release or pulling-off forces and can thus also be used at high operating pressures. However, assembly is rather awkward, since the coupling parts first have to be fitted together and then fixed manually until the clip is separately slipped on radially. This radial fitting of the clip requires a correspondingly large clearance space at the fitting location, for which reason it is not possible to use such a clip, or it is only possible to use it to a limited extent, for example in units having a plurality of plug-type connections at small center distances. In addition, there is a high risk of losing the separate clip in the state in which it is not yet fitted or in the state in which it is subsequently released again. In some applications, it is desirable nowadays to integrate a valve for discharge protection in at least one of the coupling parts. In this case, the fitting location described leads to special problems, since the coupling parts are plugged in against a valve spring force and have to be held against this spring force manually until the clip is slipped on radially. This fitting in any case requires two hands.
The object of the present invention is to improve a plug-type connection of the aforesaid type in such a way that, while retaining the advantages of the known locking principle (in particular high pulling-off forces), while the risk of losing the retaining element is reduced and the fitting is simplified. The plug type connection is especially useful in applications in which there is only a small surrounding space at the fitting location and/or in which at least one valve is to be integrated in the coupling parts.
According to the invention, the objects are achieved in that the retaining element is designed in such a way and is captively pre-fitted or can be captively pre-fitted on one of the two coupling parts in such a way that it is axially fixed with little play and is captively fixed radially and is elastically movable radially in the region of the retaining section. The retaining element, in the region of the retaining section, and the retaining web of the other coupling part being designed so as to be adapted to one another for forming a positive-locking latching connection, acting in the plug-in direction. When the coupling parts are fitted together, the retaining section is moved radially outward by the retaining web, moving relative thereto, and subsequently, in the plugged-in state, by moving back radially inward, encloses the retaining webs of the two coupling parts for the locking connection.
By this configuration according to the invention, the advantages of the known locking principle of the generic type are combined with the advantages of a plug-in latching principle. In the state of the retaining element in which it is pre-fitted on the one coupling part, only the other coupling part needs to be plugged in. Thus simple, quick and comfortable and also very reliable single-hand fitting is possible. The connection of this invention maybe used at fitting locations with a small surrounding space in the radial direction. Furthermore, release of the connection is possible by radial removal of the retaining element.